Friday, February 7, 2014

When Should the General Ability Index (GIA) be Administered?

WISC-IV (Wechsler Intelligence Scale for Children) is an IQ test used with children ages 6-16. Like other IQ Tests, the WISC-IV is designed to measure skills and abilities, rather than grade-level subject knowledge. It can be given to both readers and non-readers as it is both verbal and visual. Within the WISC there are four categories of subtests: Verbal Comprehension, Perceptual Reasoning, Working Memory, and Processing Speed.

The problem with using the WISC-IV to test some students is that sometimes the Full Scale IQ scores are excessively lowered by their Working Memory and Processing Speed scores, when averaging out the scores from all the subtests. This is unfortunate for gifted students, Dyslexic and Dysgraphic students, and gifted Dyslexics, all of whom may do poorly on Working Memory and Processing Speed.  

In an attempt to provide an alternative to this test, the General Ability Index (GAI) was implemented, which provides an IQ score derived only from the Verbal Comprehension and Perceptual Comprehension indices of the test.

When there is a statistically significant difference between one's Verbal Comprehension and Perceptual Reasoning IQ Scores, and their Working Memory and Processing Speed scores, the GAI can be calculated and reported as a representation of cognitive ability, without the influence of Working Memory and Processing Speed. This score is important because it highlights certain aspects of cognitive ability necessary for advanced or gifted placement. Thus, schools often use this score to place children in different classes (e.g., gifted or special ed.) or to predict future academic success. Processing Speed and Working Memory are both important areas of one's cognitive proficiency, however the GAI gives psychologist's an alternative method of reporting "intelligence" when these areas are weaker for many due to a variety of reasons.

The full scale IQ (FSIQ) score should not be reported if the variance from the highest to the lowest composite score is 23 or more points and if the Verbal Comprehension and Perceptual Reasoning Indices vary by less than 23 points. In this case, the GAI should be used instead.

copyright 2014   Hands On Learning Solutions – an educational diagnostic learning center.

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